Comparison of morphological and functional characteristics of primary-cultured human conjunctival epithelium and of Wong–Kilbourne derivative of Chang conjunctival cell line

Abstract

Purpose. To analyze the relevance of a human conjunctival cell line in a study of conjunctival epithelium. We investigated and compared the effects of IFNγ and TNFα in a primary culture of human conjunctiva and in a human conjunctival cell line. Methods. A primary-cultured human conjunctival epithelium and a human conjunctival cell line (Chang cells) were treated for 72 hr with 20, 200, 400 and 600 U ml −1 IFNγ or with 1100 and 11 000 U ml −1 TNFα. Then, the expression of HLA DR, CD40, CD44, CD63, CD80, CD86, Fas receptor, E-cadherin, ICAM-1, MUC1, cytokeratins and vimentin were investigated by flow cytometry. Cell morphology was studied with phalloidin staining. Apoptosis was detected by flow cytometry with Annexin V and via cell cycle analysis. Results. The primary culture of human conjunctival epithelium expressed cytokeratin K4, non-keratinized squamous epithelial marker. Chang cells presented a more dedifferentiated phenotype and were cytokeratin K4 negative. In primary-cultured cells, IFNγ (600 U ml −1) induced only a low level of apoptosis and a significant upregulation of most tested proteins such as HLA DR, Fas, ICAM-1, CD40 and CD63. In the Chang cell line, IFNγ induced a significant level of apoptosis at concentrations of 200, 400 and 600 U ml −1. HLA DR and CD63 were induced at lower levels than in primary-cultured cells. Other proteins were modified in a similar manner after IFNγ treatment in both systems. In the primary-cultured cells, TNFα induced an important upregulation of ICAM-1, Fas and CD40 whereas CD44 and CD63 were significantly decreased. Conversely, only a very weak alteration of CD63 and ICAM-1 was observed in the Chang cell line after TNFα treatment. Conclusions. A primary culture of a human conjunctival epithelium demonstrated well-defined epithelial features. TNFα and IFNγ, two inflammatory cytokines, induced different effects in both cellular systems, in a primary-cultured conjunctival epithelium and a human conjunctival cell line. Inflammation-related molecules were highly upregulated in the primary culture and, to a lesser extent, in the Chang cell line. Thus, the Chang cell line differs in certain features from a primary culture of human conjunctival epithelium, a fact which emphasizes the complexity of interpretation of in vitro data and this should be taken into consideration in in vitro studies of human conjunctival epithelium.